Lithographic printing plate precursor

ABSTRACT

A lithographic printing plate precursor is disclosed, which comprises an image-forming layer which contains a hydrophilic resin, an acid precursor and at least one component selected from fine particles containing a compound having a vinyloxy group and microcapsules containing a compound having a vinyloxy group, on a hydrophilic support, which can be development processed on a printing machine.

FIELD OF THE INVENTION

[0001] The present invention relates to a negative working (or type)lithographic printing plate precursor which comprises a hydrophilicsupport having provided thereon an image-forming layer, morespecifically relates to a lithographic printing plate precursor capableof image-recording by infrared ray scanning exposure on the basis ofdigital signals, and the image-recorded printing plate precursor can bemounted immediately on a printing machine for plate-making by on-pressdevelopment.

BACKGROUND OF THE INVENTION

[0002] A variety of studies are going ahead on the plate-makingtechnique for computer-to-plate system which has progressed increasinglyin recent years. Of such techniques, as those aiming at furtherrationalization of processes and the solution of the problem of wastesolution treatment, lithographic printing plate precursors which can bemounted on a printing machine immediately after exposure withoutundergoing development process and can be used for printing have beenresearched and various methods are suggested.

[0003] As one method of doing away with a treating process, there is amethod called on-press development comprising the steps of loading anexposed printing plate precursor onto the plate cylinder of a printingmachine and supplying a fountain solution and an ink with rotating theplate cylinder to thereby remove the non-image domain of the coatedlayer of the printing plate precursor. That is, this is a method ofexposing a lithographic printing plate precursor, loading it immediatelyonto a printing machine and effecting developing treatment in a generalprinting process.

[0004] Such a lithographic printing plate precursor suitable foron-press development is required-to have a photosensitive layer solublein a fountain solution or an ink solvent and have daylight handleabilitycapable of undergoing development on a printing machine in a brightroom.

[0005] For example, a lithographic printing plate precursor comprising ahydrophilic support having provided thereon a photosensitive layercomprising a hydrophilic binder polymer having dispersed therein fineparticles of a thermoplastic hydrophobic polymer is disclosed inJapanese Patent 2938397. This is disclosed in this patent to coalescethermoplastic hydrophobic polymer fine particles by the heat of infraredlaser exposure to form an image on a lithographic printing plateprecursor, and to mount the printing plate precursor on the cylinder ofa printing machine to perform on-press development with a fountainsolution and/or an ink. Due to the sensitive region being infrared rays,the printing plate precursor is handleable in daylight.

[0006] Further, the techniques of coalescing thermoplastic fineparticles by heat and making a printing plate by on-press developmentare also disclosed in JP-A-9-127683 (the term “JP-A” as used hereinmeans an “unexamined published Japanese patent application”) and WO99/10186.

[0007] However, these methods of making an image by the coalescence offine particles by heat are accompanied by the problem that high presslife (i.e., high printing durability) is difficult to obtain, althoughgood on-press developability can be obtained.

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to solve this problem, thatis, to provide a lithographic printing plate precursor having goodon-press developability and high press life (the term “press life” issometimes called “printing durability” or “run length”.).

[0009] The above object of the present invention has been achieved bythe following means.

[0010] (1) A lithographic printing plate precursor which comprises animage-forming layer which contains a hydrophilic resin, an acidprecursor and at least one component selected from fine particlescontaining a compound having a vinyloxy group and microcapsulescontaining a compound having a vinyloxy group, on a hydrophilic support.

[0011] (2) A lithographic printing plate precursor which comprises animage-forming layer which contains a hydrophilic resin, an acidprecursor and at least one component selected from fine particlescontaining a compound having an epoxy group and microcapsules containinga compound having an epoxy group, on a hydrophilic support.

[0012] (3) A lithographic printing plate precursor which comprises ahydrophilic support having provided thereon an image-forming layercontaining fine particles containing a thermosetting compound, and ahydrophilic resin.

[0013] (4) The lithographic printing plate precursor as described in theabove item (1), wherein the fine particles containing a compound havinga vinyloxy group or the microcapsules containing a compound having avinyloxy group contain at least one component of an acid precursor andan infrared ray-absorbing dye.

[0014] (5) The lithographic printing plate precursor as described in theabove item (1) or (4), wherein the fine particles containing a compoundhaving a vinyloxy group or the microcapsules containing a compoundhaving a vinyloxy group contain a compound having a functional groupwhich reacts with a vinyloxy group.

[0015] (6) The lithographic printing plate precursor as described in theabove item (1), (4) or (5), wherein the hydrophilic resin contains afunctional group which reacts with a vinyloxy group.

[0016] (7) The lithographic printing plate precursor as described in theabove item (2), wherein the fine particles containing a compound havingan epoxy group or the microcapsules containing a compound having anepoxy group contain at least one component of an acid precursor and aninfrared ray-absorbing dye.

[0017] (8) The lithographic printing plate precursor as described in theabove item (2) or (7), wherein the fine particles containing a compoundhaving an epoxy group or the microcapsules containing a compound havingan epoxy group contain a compound having a functional group which reactswith an epoxy group.

[0018] (9) The lithographic printing plate precursor as described in theabove item (2), (7) or (8), wherein the hydrophilic resin contains afunctional group which reacts with an epoxy group.

[0019] (10) The lithographic printing plate precursor as described inthe above item (3), wherein the fine particles containing athermosetting compound contain an infrared ray-absorbing dye.

[0020] (11) The lithographic printing plate precursor as described inthe above item (3) or (10), wherein the thermosetting compound is atleast a resin selected from a resin having a phenolic skeleton, amelamine resin and a urea resin.

[0021] (12) The lithographic printing plate precursor as described inany of the above items (1) to (11), wherein the hydrophilic support isan aluminum support which has been subjected to anodization treatmentand hydrophilization treatment.

[0022] (13) The lithographic printing plate precursor as described inany of the above items (1) to (3), wherein the printing plate precursoris development processed on a printing machine.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will be described in detail below.

[0024] Image-Forming Layer

[0025] A vinyloxy group for use in the present invention is representedby the following formula (I):

[0026] wherein R¹, R² and R³, which may be the same or different, eachrepresents a hydrogen atom, an alkyl group or an aryl group, and two ofR¹, R² and R³ may be bonded to form a saturated or olefinic unsaturatedring.

[0027] More specifically, when any of R¹, R² and R³ represents an arylgroup, the aryl group has generally from 6 to 20 carbon atoms, and maybe substituted with an alkyl group, an aryl group, an alkoxyl group, anaryloxy group, an acyl group, an acyloxy group, an alkylmercapto group,an acylamino group, an alkoxycarbonyl group, a nitro group, a sulfonylgroup, a cyano group, or a halogen atom.

[0028] When any of R¹, R² and R³ represents an alkyl group or an alkenylgroup, the alkyl group and the alkenyl group have a straight chain,branched or cyclic carbon chain generally having from 1 to 20 carbonatoms, and may be substituted with a halogen atom, a cyano group, analkoxycarbonyl group, a hydroxyl group, an alkoxyl group, an aryloxygroup, or an aryl group. Further, when any two of R¹, R² and R³ arebonded to form a ring together with the carbon atom of the vinyl group,the ring is generally a saturated or unsaturated ring having generallyfrom 3 to 8, preferably 5 or 6, carbon atoms.

[0029] In the present invention, of the vinyloxy groups represented byformula (I), a vinyloxy group wherein any one of R¹, R² and R³represents a methyl-group or an ethyl group and the remaining groupsrepresent a hydrogen atom is more preferred, and a vinyloxy group (avinyl ether group) wherein all of R¹ R² and R³ represent hydrogen atomsis particularly preferred.

[0030] As the compounds having a vinyloxy group in the presentinvention, compounds having two or more vinyloxy groups represented byformula (I) are preferred. When two or more vinyloxy groups arecontained, crosslinking can be carried out effectively, thus the effectof the present invention can be obtained easily. They are compoundshaving a boiling point of 60° C. or higher under atmospheric pressure. Acompound represented by formula (II) or (III) shown below having a vinylether group is more preferably used.

A-[O—(R⁴—O)_(n)—CH═CH₂]_(m)  (II)

A-[B—R⁴—O—CH═CH₂]_(m)  (III)

[0031] wherein A represents an m-valent alkyl group, aryl group orheterocyclic group; B represents —CO—O—, —NHCOO— or —NHCONH—; R⁴represents a straight chain or branched alkylene group having from 1 to10 carbon atoms; n represents 0 or an integer of from 1 to 10; and mrepresents an integer of from 2 to 6.

[0032] A compound represented by formula (II) can be synthesized by themethods described, e.g., in Stephen C. Lapin, Polymers Paint ColourJournal, 179 (4237),321 (1988), i.e., by the reaction of a polyhydricalcohol or a polyhydric phenol with an acetylene, or by the reaction ofa polyhydric alcohol or a polyhydric phenol with a halogenated alkylvinyl ether.

[0033] The specific examples of the compounds represented by formula(II) include ethylene glycol divinyl ether, triethylene glycol divinylether, 1,3-butanediol divinyl ether, tetramethylene glycol divinylether, neopentyl glycol divinyl ether, trimethylolpropane trivinylether, trimethylolethane trivinyl ether, hexanediol divinyl ether,1,4-cyclohexanediol divinyl ether, tetraethylene glycol divinyl ether,pentaerythritol divinyl ether, pentaerythritol trivinyl ether,pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitolpentavinyl ether, ethylene glycol diethylene vinyl ether, triethyleneglycol diethylene vinyl ether, ethylene glycol dipropylene vinyl ether,triethylene glycol diethylene vinyl ether, trimethylolpropanetriethylenevinyl ether, trimethylolpropanediethylene vinyl ether, pentaerythritoldiethylene vinyl ether, pentaerythritol triethylene vinyl ether,pentaerythritol tetraethylene vinyl ether, 1,2-di(vinyl ethermethoxy)benzene, 1,2-di (vinyl ether ethoxy)benzene, and the followingcompounds represented by formulae (M-1) to (M-41), but the presentinvention is not limited thereto.

[0034] On the other hand, a compound represented by formula (III) (thecase where B represents —CO—O—) can be produced by the reaction of apolyvalent carboxylic acid with a halogenated alkyl vinyl ether. Thespecific examples thereof include diethylene vinyl ether terephthalate,diethylene vinyl ether phthalate, diethylene vinyl ether isophthalate,dipropylene vinyl ether phthalate, dipropylene vinyl etherterephthalate, dipropylene vinyl ether isophthalate, diethylene vinylether maleate, diethylene vinyl ether fumarate, and diethylene vinylether itaconate, but the present invention is not limited thereto.

[0035] Further, as the compound having a vinyloxy group preferably usedin the present invention, a vinyloxy group-containing compoundsynthesized by the reaction of a vinyloxy compound having activehydrogen represented by the following formula (IV), (V) or (VI) with acompound having an isocyanate group can be exemplified.

CH₂═CH—O—R⁵—OH  (IV)

CH₂═CH—O—R⁵—COOH  (V)

CH₂═CH—O—R⁵—NH₂  (VI)

[0036] wherein R⁵ represents a straight chain or branched alkylene grouphaving from 1 to 10 carbon atoms. As the compound having an isocyanategroup, the compounds described, e.g., in Kakyo-zai Handbook(Crosslinking Agent Handbook), Taiseisha Co., Ltd. (1981) can be used.

[0037] The specific examples of the compounds represented by formula(III) include polyisocyanate type compounds, e.g., triphenylmethanetriisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, adimer of 2,4-tolylene diisocyanate, naphthalene-1,5-diisocyanate,o-tolylene diisocyanate, polymethylenepolyphenyl isocyanate, andhexamethylene diisocyanate, and polyisocyanate adducts type compounds,e.g., adducts of tolylene diisocyanate and trimethylolpropane, adductsof hexamethylene diisocyanate and water, and adducts of xylylenediisocyanate and trimethylolpropane.

[0038] A variety of compounds having vinyloxy groups at terminals can besynthesized by reacting these isocyanate group-containing compounds withcompounds containing an active hydrogen-containing vinyloxy group. Theexamples of the compounds having a vinyloxy group for use in the presentinvention are shown below, but the present invention is not limitedthereto.

[0039] Further, as the compounds having a vinyloxy group preferably usedin the present invention, the polymer having a vinyloxy group on theside chain can be exemplified. The specific examples of the polymers areshown below.

[0040] As the compounds having an epoxy group according to the presentinvention, the compounds having two or more epoxy groups are preferred.When two or more epoxy groups are contained, crosslinking can be carriedout effectively, thus the effect of the present invention can beobtained easily.

[0041] As the compound having an epoxy group for use in the presentinvention, the glycidyl ether compounds obtained by the reaction ofpolyhydric alcohols and polyhydric phenols with epichlorohydrin, theprepolymers thereof, polymers and copolymers of acrylic acid ormethacrylic acid glycidyl, etc., can be exemplified.

[0042] The specific examples of the preferred compounds having an epoxygroup include propylene glycol diglycidyl ether, tripropylene glycoldiglycidyl ether, polypropylene glycol diglycidyl ether, neopentylglycol diglycidyl ether, trimethylolpropane triglycidyl ether,diglycidyl ether of hydrogenated bisphenol A, hydroquinone diglycidylether, resorcinol diglycidyl ether, diglycidyl ether of bisphenol A orepichlorohydrin adducts of bisphenol A, diglycidyl ether of bisphenol For epichlorohydrin adducts of bisphenol F, diglycidyl ether ofhalogenated bisphenol A or epichlorohydrin adducts of halogenatedbisphenol A, diglycidyl ether of biphenyl type bisphenol orepichlorohydrin adducts of biphenyl type bisphenol, glycidyl etherifiedproducts of novolak resins, methyl methacrylate/glycidyl methacrylatecopolymers, and ethyl methacrylate/glycidyl methacrylate copolymers.

[0043] As the commercially available products of these compounds, forexample, Epikote 1001 (molecular weight: about 900, epoxy equivalent:from 450 to 500), Epikote 1002 (molecular weight: about 1,600, epoxyequivalent: from 600 to 700), Epikote 1004 (molecular weight: about1,060, epoxy equivalent: from 875 to 975), Epikote 1007 (molecularweight: about 2,900, epoxy equivalent: 2,000), Epikote 1009 (molecularweight: about 3,750, epoxy equivalent: 3,000), Epikote 1010 (molecularweight: about 5,500, epoxy equivalent: 4,000), Epikote 1100L (epoxyequivalent: 4,000), and Epikote YX31575 (epoxy equivalent: 1,200) (allof which are the products of Yuka Shell Epoxy Co., Ltd.), and SumiepoxyESCN-195XHN, ESCN-195XL, ESCN-195XF (manufactured by Sumitomo ChemicalCo., Ltd.) can be exemplified.

[0044] The thermosetting compound for use in the present invention is alow molecular weight compound containing a thermosetting resin and ahydroxymethyl group or an alkoxymethyl group.

[0045] The thermosetting resins preferably used in the present inventioninclude resins having a phenolic skeleton, urea-based resins (e.g., urearesins obtained by resinifying urea or urea derivatives such asmethoxymethylurea with aldehydes such as formaldehyde), melamine resins(e.g., melamine resins obtained by resinifying melamine or melaminederivatives with aldehydes such as formaldehyde), alkyd resins,unsaturated polyester resins, and polyurethane resins.

[0046] As the resins having a preferred phenolic skeleton, e.g.,phenolic resins obtained by resinifying phenol or cresol with aldehydessuch as formaldehyde, hydroxystyrene resins, methacrylamide oracrylamide resins having a phenolic skeleton, e.g.,N-(p-hydroxyphenyl)methacrylamide, and methacrylate or acrylate resinshaving a phenolic skeleton, e.g., N-(p-hydroxyphenyl) methacrylate, canbe exemplified.

[0047] Of these, resins having a phenolic skeleton, melamine resins andurea resins are particularly preferred.

[0048] Compounds having a molecular weight of 1,000 or less arepreferably used in the present invention as the low molecular weightcompound having a hydroxymethyl group or an alkoxymethyl group, and amethoxymethyl group and an ethoxymethyl group are preferably used in thepresent invention as the alkoxymethyl group.

[0049] The specific examples of the low molecular weight compoundshaving a hydroxymethyl group or an alkoxymethyl group include 2,4,6-tris(ethoxymethyl)phenol, 4-chloro-2,6-bis(ethoxyethyl)phenol,2,6-bis(hydroxyethyl)-p-toluene, 2,6-bis(ethoxymethyl)-p-toluene,compounds represented by the following formulae (T1) and (T2), andmelamine derivatives, e.g., methoxymethylmelamines.

[0050] The fine particles containing the above-described compoundshaving a vinyloxy group or an epoxy group, or the fine particlescontaining a thermosetting resin can be obtained by a solventevaporation method comprising the steps of dissolving these compounds orresins alone or as a mixture of two or more in a non-aqueous organicsolvent, mixing the resulting solution with an aqueous solutioncontaining a dispersant and emulsifying the solution, and thensolidifying the emulsion into fine particles with heating to evaporatethe organic solvent, but the present invention is not limited thereto.

[0051] The fine particles containing these compounds or resins togetherwith infrared ray-absorbing dyes are also preferably used in the presentinvention. Further, in the case of the fine particles containing thecompounds having a vinyloxy group or an epoxy group, it is alsopreferred to coexist an acid precursor with these compounds. In the caseof the fine particles containing the compounds having a vinyloxy groupor an epoxy group, it is also preferred to contain a compound having afunctional group which reacts with a vinyloxy group or an epoxy group(the other compound of the reaction) in the fine particles. Thecoexistence of an infrared ray-absorbing dye, an acid precursor and/orthe other compound of the reaction in the fine particles can beperformed according to the above solvent evaporation method. That is,the coexistence can be effected by dissolving an infrared ray-absorbingdye, an acid precursor and/or the other compound of the reactiontogether when the compounds having a vinyloxy group or an epoxy groupare dissolved in a non-aqueous organic solvent and performing thesolvent evaporation method.

[0052] The compound having a vinyloxy group or an epoxy group can bemicro-encapsulated by well-known methods. For example, as themanufacturing method of the microcapsules, the method making use ofcoacervation as disclosed in U.S. Pat. Nos. 2,800,457 and 2,800,458, theinterfacial polymerization method as disclosed in British Patent990,443, U.S. Pat. No. 3,287,154, JP-B-38-19574 (the term “JP-B” as usedherein means an “examined Japanese patent publication”), JP-B-42-446,and JP-B-42-711, the method by the deposition of a polymer as disclosedin U.S. Pat. Nos. 3,418,250 and 3,660,304, the method using isocyanatepolyol wall materials as disclosed in U.S. Pat. No. 3,796,669, themethod using isocyanate wall materials as disclosed in U.S. Pat. No.3,914,511, the method using urea-formaldehyde series orurea-formaldehyde-resorcinol series wall materials as disclosed in U.S.Pat. Nos. 4,001,140, 4,087,376 and 4,089,802, the method using wallmaterials, such as melamine-formaldehyde resins and hydroxy cellulose,as disclosed in U.S. Pat. No. 4,025,445, the monomer polymerization insitu method as disclosed in JP-B-36-9163 and JP-B-51-9079, the spraydrying method as disclosed in British Patent 930,422 and U.S. Pat. No.3,111,407, and the electrolytic dispersion cooling method as disclosedin British Patents 952,807 and 967,074 can be exemplified, but thepresent invention is not limited thereto.

[0053] The microcapsule walls preferably used in the present inventionhave three dimensional crosslinking and a property of swelling by asolvent. From this point of view, polyurea, polyurethane, polyester,polycarbonate, polyamide, and the mixtures of these compounds arepreferably used as the microcapsule wall materials, and polyurea andpolyurethane are particularly preferred.

[0054] The microcapsule according to the present invention can besynthesized so as to contain a solvent in the dispersion medium fordissolving the contents encapsulated and swelling the wall material. Thediffusion of the contents out of the microcapsule is accelerated by thesolvent.

[0055] Such solvents depend upon the dispersion media of microcapsules,the materials and the wall thicknesses of microcapsule walls, and thecontents of microcapsules, but they can be selected easily from manycommercially available products. For example, in the case of amicrocapsule of aqueous dispersion comprised of crosslinked polyurea orpolyurethane wall, alcohols, ethers, acetals, esters, ketones,polyhydric alcohols, amides, amines and fatty acids are preferably usedas the solvent.

[0056] As the specific examples of the solvents, methanol, ethanol,tertiary butanol, n-propanol, tetrahydrofuran, methyl lactate, ethyllactate, methyl ethyl ketone, propylene glycol monomethyl ether,ethylene glycol diethyl ether, ethylene glycol monomethyl ether,γ-butyrolactone, N,N-dimethylformamide, and N,N-dmethylacetamide can beexemplified, but the present invention is not limited thereto. Thesesolvents may be used in combination of two or more.

[0057] Solvents which are insoluble in microcapsule dispersion solutionsbut are soluble when the above solvents are mixed can also be used inthe present invention. The addition amount of the solvent is decideddepending upon the combination of the materials but when it is less thanthe optimal amount, image-forming property is insufficient, while whenit is too much, the stability of the dispersion solution isdeteriorated. The addition amount is in general from 5 to 95 wt %,preferably from 10 to 90 wt %, and more preferably from 15 to 85 wt %,based on the coating solution.

[0058] The average particle size of the fine particles and microcapsulescontaining a compound having a vinyloxy group or an epoxy group ispreferably from 0.01 to 3.0 μm, more preferably from 0.05 to 2.0 μm, andparticularly preferably from 0.08 to 1.0 μm. The average particle sizeof the fine particles containing a thermosetting compound is preferablyfrom 0.01 to 2.0 μm. Good resolving power and storage stability can beobtained with this range of particle size.

[0059] The addition amount of the fine particles and the microcapsulescontaining a compound having a vinyloxy group or an epoxy group to theimage-forming layer is preferably 50 wt % or more, more preferably 60 wt% or more, based on the solid contents of the image-forming layer. Theaddition amount of the fine particles containing a thermosettingcompound to the image-forming layer is preferably from 40 to 98 wt %,more preferably from 50 to 95 wt %, based on the solid contents of theimage-forming layer. Good on-press developing property and high presslife (i.e., high printing durability) can be obtained with this range ofaddition amount.

[0060] The fine particles containing a compound having a vinyloxy groupor an epoxy group according to the present invention can contain acompound having a functional group which reacts with a vinyloxy group oran epoxy group. As the preferred functional groups which react with avinyloxy group, there can be exemplified a carboxyl group and a hydroxylgroup. The compounds having two or more functional groups are preferablyused in the present invention. Either low molecular weight compounds orhigh molecular weight compounds can be used.

[0061] The specific examples of such low molecular weight compoundsinclude 1,4-bis(2-hydroxyethyloxy)benzene,1,3,5-tris(2-hydroxyethyloxy)benzene, bisphenol A,2,2-bis(4-hydroxymethyloxyphenyl)propane,2,2-bis[4-(2-hydroxyethyloxy)phenyl]propane,4,4′-bis(2-hydroxyethyloxy)biphenyl, and1,1,1-tris(4-hydroxyphenyl)ethane.

[0062] As the high molecular weight compounds which react with avinyloxy group, the polymers and copolymers of monomers having acarboxyl group, e.g., acrylic acid, methacrylic acid, maleic acid,itaconic acid, crotonic acid, isocrotonic acid, p-vinylbenzoic acid,p-vinylcinnamic acid, and maleic acid monomethyl ether, and monomershaving a hydroxyl group, e.g., 2-hydroxyethyl acrylate, 2-hydroxyethylmethacrylate, p-hydroxystyrene, halogenated hydroxystyrene,N-(4-hydroxyphenyl) acrylamide, N-(4-hydroxyphenyl)methacrylamide,(4-hydroxyphenyl) acrylate, and (4-hydroxyphenyl) methacrylate can beexemplified.

[0063] Further, as the high molecular weight compounds which react witha vinyloxy group, the copolymers with other monomers which arecopolymerizable with the above monomers can also be used. As suchcopolymerizable monomers, e.g., acrylonitrile, acrylamide,methacrylamide, methyl acrylate, ethyl acrylate, propyl acrylate, butylacrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate,propyl methacrylate, butyl methacrylate, benzyl methacrylate, vinylbenzoate, vinyl chloride, vinylidene chloride, styrene, vinyl acetate,butadiene, chloroprene, and isoprene can be exemplified, but the presentinvention is not limited thereto.

[0064] As some other high molecular weight compounds which react with avinyloxy group, linear high molecular weight compounds having a carboxylgroup and a hydroxyl group obtained by the co-condensation of dihydroxycompounds having a carboxyl group with dicarboxylic acid compounds canbe exemplified. For example, linear polyurethane resins having acarboxyl group obtained by reacting dihydroxy compounds having acarboxyl group such as 3,5-dihydroxybenzoic acid,2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(2-hydroxyethyl)propionicacid, 2,2-bis(3-hydroxypropyl)propionic acid, bis (hydroxymethyl)aceticacid, bis (4-hydroxyphenyl) acetic acid,4,4-bis(4-hydroxyphenyl)pentanoic acid, or tartaric acid with theequivalent amount of diisocyanate compounds such as 2,4-tolylenediisocyanate, dimers of 2,4-tolylene diisocyanate, 4,4′-diphenylmethanediisocyanate, 1,5-naphthylene diisocyanate, hexamethylene diisocyanate,trimethylhexamethylene diisocyanate, 4,4′-methylenebis(cyclohexylisocyanate), etc., can be exemplified. Further, compounds using diolcompounds which do not have a carboxyl group and may have some othersubstituents which do not react with isocyanate, e.g., ethylene glycol,diethylene glycol, triethylene glycol, neopentyl glycol, 1,3-butyleneglycol, bisphenol A, hydrogenated bisphenol A, hydrogenated bisphenol F,ethylene oxide adducts of bisphenol A, etc., in combination may also beused.

[0065] As still other high molecular weight compounds which react with avinyloxy group, diols having the above carboxyl group and, if necessary,polyesters having a carboxyl group obtained by the co-condensation ofthe above other diols with a bifunctional carboxylic acid, e.g.,phthalic acid, isophthalic acid, terephthalic acid, fumaric acid,itaconic acid, adipic acid, etc., can be exemplified.

[0066] As the preferred functional groups which react with an epoxygroup, there can be exemplified a carboxyl group and an aromatichydroxyl group. The compounds having two or more these functional groupsare preferably used in the present invention. Either low molecularweight compounds or high molecular weight compounds can be used.

[0067] The specific examples of such low molecular weight compoundsinclude bisphenol A, 4,4′-dihydroxybiphenyl, and1,1,1-tris(4-hydroxyphenyl)ethane.

[0068] As the high molecular weight compounds which react with an epoxygroup, the polymers and copolymers of monomers having a carboxyl group,e.g., acrylic acid, methacrylic acid, maleic acid, itaconic acid,crotonic acid, isocrotonic acid, p-vinylbenzoic acid, p-vinylcinnamicacid, and maleic acid monomethyl ether, and monomers having a hydroxylgroup, e.g. p-hydroxystyrene, halogenated hydroxystyrene,N-(4-hydroxyphenyl)acrylamide, N-(4-hydroxyphenyl)methacrylamide,(4-hydroxyphenyl) acrylate, and (4-hydroxyphenyl) methacrylate can beexemplified.

[0069] Further, as the high molecular weight compounds which react withan epoxy group, the copolymers with other monomers which arecopolymerizable with the above monomers can also be used. As suchcopolymerizable monomers, e.g., acrylonitrile, acrylamide,methacrylamide, methyl acrylate, ethyl acrylate, propyl acrylate, butylacrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate,propyl methacrylate, butyl methacrylate, benzylmethacrylate,vinylbenzoate, vinyl chloride, vinylidene chloride, styrene, vinylacetate, butadiene, chloroprene, and isoprene can be exemplified, butthe present invention is not limited thereto.

[0070] As some other high molecular weight compounds which react with anepoxy group, linear high molecular weight compounds having a carboxylgroup and a hydroxyl group obtained by the co-condensation of dihydroxycompounds having a carboxyl group with dicarboxylic acid compounds canbe exemplified. For example, linear polyurethane resins having acarboxyl group obtained by reacting dihydroxy compounds having acarboxyl group such as 3,5-dihydroxybenzoic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(2-hydroxyethyl)propionic acid,2,2-bis(3-hydroxypropyl)propionic acid, bis(hydroxymethyl)acetic acid,bis(4-hydroxyphenyl)acetic acid, 4,4-bis(4-hydroxyphenyl)pentanoic acid,or tartaric acid with the equivalent amount of diisocyanate compoundssuch as 2,4-tolylene diisocyanate, dimers of 2,4-tolylene diisocyanate,4,4′-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate,hexamethylene diisocyanate, trimethylhexamethylene diisocyanate,4,4′-methylenebis(cyclohexyl isocyanate), etc., can be exemplified.Further, compounds using diol compounds which do not have a carboxylgroup and may have some other substituents which do not react withisocyanate, e.g., ethylene glycol, diethylene glycol, triethyleneglycol, neopentyl glycol, 1,3-butylene glycol, bisphenol A, hydrogenatedbisphenol A, hydrogenated bisphenol F, ethylene oxide adducts ofbisphenol A, etc., in combination may also be used.

[0071] As still other high molecular weight compounds which react withan epoxy group, diols having the above carboxyl group and, if necessary,polyesters having a carboxyl group obtained by the co-condensation ofthe above other diols with a bifunctional carboxylic acid, e.g.,phthalic acid, isophthalic acid, terephthalic acid, fumaric acid,itaconic acid, adipic acid, etc., can be exemplified.

[0072] As other compounds which react with a vinyloxy group or an epoxygroup, phenol resins such as novolak resins, e.g., phenol-formaldehyderesins, m-cresol-formaldehyde resins, p-cresol-formaldehyde resins,o-cresol-formaldehyde resins, m-/p-mixed cresol-formaldehyde resins, andphenol-cresol-formaldehyde resins, resol type phenol resins, andphenol-modified xylene resins can be exemplified.

[0073] The microcapsules encapsulating a compound having a vinyloxygroup or an epoxy group according to the present invention canencapsulate a compound having a functional group which reacts with avinyloxy group or an epoxy group. As the preferred functional groupwhich can be encapsulated in the microcapsules is a hydroxyl group, andthe above-described compounds having a hydroxyl group can be preferablyused.

[0074] The addition amount of the compound having a functional groupwhich reacts with a vinyloxy group or an epoxy group is preferably from1 to 95 wt %, more preferably from 20 to 90 wt %, and most preferablyfrom 30 to 80 wt %, based on the solid contents of the fine particles ormicrocapsules containing a compound having a vinyloxy group or an epoxygroup.

[0075] The image-forming layer according to the present inventioncontains a hydrophilic resin for the purpose of enhancing the on-pressdeveloping property and the film strength of the image-forming layeritself. As the hydrophilic resins, e.g., resins having a film-formingproperty having a hydrophilic group such as a hydroxyl group, a carboxylgroup, a phosphoric acid group, a sulfonic acid group, or an amido groupare preferably used. Further, when a hydrophilic resin is reacted with avinyloxy group or an epoxy group and crosslinked, the image strength isincreased and the press life is improved, hence hydrophilic resinshaving functional groups which react with these groups are preferred.Above all, if the compound having a vinyloxy group is used, ahydrophilic resin having a hydroxyl group or a carboxyl group ispreferred, and if the compound having an epoxy group is used, ahydrophilic resin having a carboxyl group is preferred.

[0076] The specific examples of hydrophilic resins include gum arabic,casein, gelatin, starch derivatives, soybean glue, hydroxypropylcellulose, methyl cellulose, carboxymethyl cellulose and sodium saltsthereof, cellulose acetate, sodium alginate, vinyl acetate-maleic acidcopolymers, styrene-maleic acid copolymers, polyacrylic acids and thesalts thereof, polymethacrylic acids and the salts thereof, homopolymersand copolymers of hydroxyethyl methacrylate, homopolymers and copolymersof hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropylmethacrylate, homopolymers and copolymers of hydroxypropyl acrylate,homopolymers and copolymers of hydroxybutyl methacrylate, homopolymersand copolymers of hydroxybutyl acrylate, polyethylene glycols,hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinylacetate having the degree of hydrolysis of 60 wt % and preferably atleast 80 wt %, polyvinyl formal, polyvinyl pyrrolidone, homopolymers andcopolymers of acrylamide, homopolymers and copolymers of methacrylamide,homopolymers and copolymers of N-methylolacrylamide, homopolymers andcopolymers of 2-acrylamide-2-methyl-1-propanesulfonic acid, andhomopolymers and copolymers of 2-methacryloyloxyethylsulfonic acid.

[0077] Moreover, the above-described hydrophilic resin may becrosslinked to such a degree that the unexposed domain may be developedon a printing machine. As the crosslinking agents, aldehyde resins,e.g., glyoxal, melamine-formaldehyde resins, and urea-formaldehyderesins, methylol compounds, e.g., N-methylolurea, N-methylolmelamine,and methylolated polyamide resins, active vinyl compounds, e.g.,divinylsulfone and (B-hydroxyethylsulfonic acid), epoxy compounds, e.g.,epichlorohydrin, polyethylene glycol diglycidyl ether, polyamide,polyamine, epichlorohydrin adducts, and polyamide-epichlorohydrinresins, ester compounds, e.g., monochloroacetic acid ester andthioglycolic acid ester, polycarboxylic acids, e.g., polyacrylic acidand methyl vinyl ether-maleic acid copolymer, inorganic crosslinkingagents, e.g., boric acid, titanyl sulfate, Cu, Al, Sn, V, Cr salts, andmodified polyamideimide resins can be exemplified.

[0078] In addition, such crosslinking agents as ammonium chloride, asilane coupling agent, a titanate coupling agent can be used incombination.

[0079] The acid precursor for use in the image-forming layer in thepresent invention generates an acid at exposure and initiates oraccelerates the reaction of a compound having a vinyloxy group or anepoxy group. Although the acid precursor may be contained in thehydrophilic resin of the image-forming layer, it is preferred that theacid precursor be contained in the fine particles containing a compoundhaving a vinyloxy group or an epoxy group or the microcapsulescontaining a compound having a vinyloxy group or an epoxy group from thepoint of capable of easily obtaining high sensitivity and high presslife.

[0080] As the acid precursors for use in the present invention,photo-initiators of photo-cationic polymerization, photo-initiators ofphoto-radical polymerization, photo-decolorants of dyes,photo-discolorants, well-known acid-generating agents for use inmicroresists, etc., well-known acid-generating compounds by thermaldecomposition, and mixtures of these compounds can be arbitrarilyselected.

[0081] As the acid precursors preferably used in a compound having avinyloxy group, onium salts such as the diazonium salts described in S.I. Schlesinger, Photogr. Sci. Eng., 18, 387 (1974), and T. S. Bal etal., Polymer, 21, 423 (1980), the ammonium salts disclosed in U.S. Pat.Nos. 4,069,055, 4,069,056, Re 27,992, and JP-A-4-365049, the phosphoniumsalts described in D. C. Necker et al., Macromolecules, 17, 2468 (1984),C. S. Wen et al., Teh, Proc. Conf. Rad. Curing ASIA, p. 478, Tokyo,October (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056, the iodoniumsalts described in J. V. Crivello et al., Macromolecules, 10 (6), 1307(1977), Chem. & Eng. News, November 28, p.31(1988), EP104143,JP-A-2-150848, and JP-A-2-296514, the sulfonium salts described in J. V.Crivello et al., Polymer J., 17, 73 (1985), J. V. Crivello et al., J.Org. Chem., 43, 3055 (1978), W. R. Watt et al., J. Polymer Sci., PolymerChem. Ed., 22, 1789 (1984), J. V. Crivello et al., Polymer Bull., 14,279 (1985), J. V. Crivello et al., Macromolecules, 14 (5), 1141 (1981),J. V. Crivello et al., J. Polymer Sci., Polymer Chem. Ed., 17, 2877(1979), EP 370693, U.S. Pat. No. 3,902,114, EP 233567, EP 297443, EP297442, U.S. Pat. No. 4,933,377, U.S. Patents 4,760,013, 4,734,444,2,833,827, German Patents 2,904,626, 3,604,580, and 3,604,581, theselenonium salts described in J. V. Crivello et al., Macromolecules, 10(6), 1307 (1977), and J. V. Crivello et al., J. Polymer Sci., PolymerChem. Ed., 17, 1047 (1979), the arsonium salt, etc., described in C. S.Wen et al., Teh, Proc. Conf. Rad. Curing ASIA, p. 478, Tokyo, October(1988); the organic halide compounds disclosed in U.S. Pat. No.3,905,815, JP-B-46-4605, JP-A-48-36281, JP-A-55-32070, JP-A-60-239736,JP-A-61-169835, JP-A-61-169837, JP-A-62-58241, JP-A-62-212401,JP-A-63-70243, and JP-A-63-298339; the organic metal/organic halidecompounds described in K. Meier et al., J. Rad. Curing, 13 (4), 26(1986), T. P. Gill et al., Inorg. Chem., 19, 3007 (1980), D. Astruc,Acc. Chem. Res., 19 (12), 377 (1896) and JP-A-2-161445; the light/acidgenerating agents having o-nitrobenzyl type protective group describedin S. Hayase et al., J. Polymer Sci., 25, 753 (1987), E. Reichmanis etal., J. Polymer Sci., Polymer Chem. Ed., 23, 1 (1985), Q. Q. Zhu et al.,J. Photochem., 36, 85, 39, 317 (1987), B. Amit et al., TetrahedronLett., (24), 2205 (1973), D. H. R. Barton et al., J. Chem. Soc., 3571(1965), P. M. Collins et al., J. Chem. Soc., Perkin I, 1695 (1975), M.Rudinstein et al., Tetrahedron Lett., (17), 1445 (1975), J. W. Walker etal., J. Am. Chem. Soc., 110, 7170 (1988), S. C. Busman et al., J.Imaging Technol., 11 (4), 191 (1985), H. M. Houlihan et al.,Macromolecules, 21, 2001 (1988), P. M. Collins et al., J. Chem. Soc.,Chem. Commun., 532 (1972), S. Hayase et al., Macromolecules, 18, 1799(1985), E. Reichmanis et al., J. Electrochem. Soc., Solid State Sci.Technol., 130 (6), F. M. Houlihan et al., Macromolecules, 21, 2001(1988), EP 0290750, EP 046083, EP 156535, EP 271851, EP 0388343, U.S.Pat. Nos. 3,901,710, 4,181,531, JP-A-60-198538, and JP-A-53-133022; thecompounds which generate a sulfonic acid by photolysis represented byiminosulfonate described in M. Tunook et al., Polymer Preprints, Japan,38 (8), G. Berner et al., J. Rad. Curing, 13 (4), W. J. Mijs et al.,Coating Technol., 55 (697), 45 (1983), Akzo, H. Adachi et al., PolymerPreprints, Japan, 37 (3), EP 0199672, EP 84515, EP 199672, EP 044115, EP0101122, U.S. Pat. Nos. 4,618,564, 4,371,605, 4,431,774, JP-A-64-18143,JP-A-2-245756, and JP-A-4-365048; and the disulfone compounds disclosedin JP-A-61-166544 can be exemplified.

[0082] Further, the compounds having introduced these acid-generatinggroups or compounds into the polymer main chains or side chains asdescribed, e.g., in M. E. Woodhouse et al., J. Am. Chem. Soc., 104, 5586(1982), S. P. Pappas et al., J. Imaging Sci., 30 (5), 218 (1986), S.Kondo et al., Makromol. Chem., Rapid Commun., 9, 625 (1988), Y. Yamadaet al., Makromol. Chem., 152, 153, 163 (1972), J. V. Crivello et al., J.Polymer Sci., Polymer Chem. Ed., 17, 3845 (1979), U.S. Pat. No.3,849,137, German Patent 3,914,407, JP-A-63-26653, JP-A-55-164824,JP-A-62-69263, JP-A-63-1460387, JP-A-63-163452, JP-A-62-153853, andJP-A-63-146029 can be used in the present invention.

[0083] Further, the compounds which generate acids by light, e.g.,described in V. N. R. Pillai, Synthesis, (1), 1 (1980), A. Abad et al.,Tetrahedron Lett., (47), 4555 (1971), D. E. R. Barton et al., J. Chem.Soc., (C), 329 (1970), U.S. Pat. No. 3,779,778 and EP 12712 can also beused. More specifically, the following compounds can be exemplified.

[0084] When a compound having an epoxy group is used, onium salts, suchas a diazonium salt, an ammonium salt, a phosphonium salt, an iodoniumsalt, a sulfonium salt, a selenonium salt and an arsonium salt of theabove-described acid precursors are preferably used and, above all,onium salts having counter anions of oniums of BF₄ ⁻, PF₆ ⁻, AsF₆ ⁻,SBF₆ ⁻, etc., are more preferred. The specific examples of the oniumsalts are shown below, but the present invention is not limited thereto.

[0085] The addition amount of the acid precursors is preferably from0.01 to 20 wt %, more preferably from 0.1 to 10 wt %, based on the totalsolid contents of the image-forming layer.

[0086] The image-forming layer of the present invention can contain aninfrared ray-absorbing dye for the purpose of increasing the infraredabsorbing efficiency to enhance sensitivity. Although the infraredray-absorbing dye may be contained in the hydrophilic resin of theimage-forming layer, it is preferred that the dye be contained in thefine particles or the microcapsules from the point of capable of easilyobtaining high sensitivity and high press life.

[0087] Such infrared ray-absorbing dyes may be sufficient so long asthey are light-absorbing substances having absorption band at least inapart of the wavelength of from 700 to 1,200 nm, and various kinds ofpigments, dyes and metal particles can be used.

[0088] As such pigments, commercially available pigments and infraredray-absorbing pigments described in Color Index (C.I.) Binran (ColorIndex Handbook), Saishin Ganryo Binran (The Latest Pigment Handbook),compiled by Nihon Ganryo Gijutsu Kyokai (1977), Saishin Ganryo OyoGijutsu (The Latest Pigment Applied Technique), published by CMCPublishing Co. (1986), Insatsu Ink Gijutsu (Printing Ink Technique), CMCPublishing Co. (1984) can be used.

[0089] These pigments may be surface-treated by well-known surfacetreatment methods, if necessary, for improving the dispersibility in thelayer to be added. As methods of surface treatments, a method ofsurface-coating with hydrophilic resins and lipophilic resins, a methodof adhering surfactants, and a method of attaching reactive substances(e.g., silica sol, alumina sol, silane coupling agents, epoxy compounds,isocyanate compounds, etc.) on the surfaces of pigments can beexemplified.

[0090] The pigments to be added to a hydrophilic layer are preferablysurface-coated with hydrophilic resins or silica sol so as to bedispersed with water-soluble resins and not to impair the hydrophilicproperty. The particle size of the pigments is preferably from 0.01 to 1μm, more preferably from 0.01 to 0.5 μm. Well-known dispersing methodsused in manufacturing inks and toners can be used as dispersing methodsof pigments.

[0091] Carbon black can be exemplified as a particularly preferredpigment.

[0092] As the dyes for this purpose, commercially available dyes andwell-known dyes described, for example, in Senryo Binran (Dye Handbook),compiled by Yuki Gosei Kagaku Kyokai (1970), “Kin-Sekigai Kyushu Shikiso(Near Infrared Ray Absorbing Dyes)” in Kagaku Kogyo (Chemical Industry),pp. 45 to 51 (May, 1986), 90 Nen-dai Kinosei Shikiso no Kaihatsu toShijo Doko (Development and Market Trend of Functional Dyes in theNineties), Item 2.3, Chapter 2, CMC Publishing Co. Ltd. (1990), orvarious patent specifications can be utilized. Specifically, infraredray-absorbing dyes, e.g., azo dyes, metal complex azo dyes, pyrazoloneazo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes,quinoneimine dyes, polymethine dyes, and cyanine dyes are preferablyused.

[0093] Further, as infrared ray-absorbing dyes, e.g., the cyanine dyesdisclosed in JP-A-58-125246, JP-A-59-84356, and JP-A-60-78787, themethine dyes disclosed in JP-A-58-173696, JP-A-58-181690, andJP-A-58-194595, the naphthoquinone dyes disclosed in JP-A-58-112793,JP-A-58-224793, JP-A-59-48187, JP-A-59-73996, JP-A-60-52940, andJP-A-60-63744, the squarylium dyes disclosed in JP-A-58-112792, thecyanine dyes disclosed in British Patent 434,875, the dyes disclosed inU.S. Pat. No. 4,756,993, the cyanine dyes disclosed in U.S. Pat. No.4,973,572, the dyes disclosed in JP-A-10-268512, and the phthalocyaninecompounds disclosed in JP-A-11-235883 can be exemplified.

[0094] Further, the near infrared ray-absorbing sensitizing dyesdisclosed in U.S. Pat. No. 5,156,938 are also preferably used. Inaddition, the substituted arylbenzo(thio)pyrylium salts disclosed inU.S. Pat. No. 3,881,924, the trimethine thiapyrylium salts disclosed inJP-A-57-142645, the pyrylium-based compounds disclosed inJP-A-58-181051, JP-A-58-220143, JP-A-59-41363, JP-A-59-84248,JP-A-59-84249, JP-A-59-146063, and JP-A-59-146061, the cyanine dyesdisclosed in JP-A-59-216146, the pentamethine thiopyrylium saltsdisclosed in U.S. Pat. No. 4,283,475, the pyrylium compounds disclosedin JP-B-5-13514 and JP-B-5-19702, Epolite III-178, Epolite III-130, andEpolite III-125 (manufactured by Epoline Co., Ltd.) are also preferablyused.

[0095] Of these dyes, the dyes which are preferably used in thehydrophilic matrix such as the hydrophilic resin of the image-forminglayer are water-soluble dyes and specific examples are shown below.

[0096] As the infrared ray-absorbing dyes added into the hydrophobiccompounds in the fine particles and the microcapsules in theimage-forming layer in the present invention, the above infraredray-absorbing dyes may be used but lipophilic dyes are more preferred.The following dyes can be exemplified as the specific examples.

[0097] The above-described organic infrared ray-absorbing dyes can beadded to the image-forming layer in an amount of up to 30 wt %,preferably from 5 to 25 wt %, and particularly preferably from 6 to 20wt %. Good sensitivity can be obtained with this range of additionamount.

[0098] The image-forming layer of the present invention can also containmetallic fine particles as the infrared ray-absorbing dyes. Manymetallic fine particles are light-to-heat convertible and alsoself-exothermic at the same time.

[0099] Examples of preferred metallic fine particles include the fineparticles of simple substances or alloys of Si, Al; Ti, V, Cr, Mn, Fe,Co, Ni, Cu, Zn, Y, Zr, Mo, Ag, Au, Pt, Pd, Rh, In, Sn, W, Te, Pb, Ge,Re, Sb, etc., or oxides or sulfides of them.

[0100] The preferred metals among the metals constituting these metallicfine particles are metals having a melting point of about 1,000° C. orless at which they are easily fused by light irradiation and havingabsorption in the infrared, visible or ultraviolet region, e.g., Re, Sb,Te, Au, Ag, Cu, Ge, Pb and Sn.

[0101] Further, metallic fine particles having a relatively low meltingpoint and comparatively high heat absorbance, e.g., Ag, Au, Cu, Sb, Geand Pb, are especially preferred, and most preferred elements are Ag, Auand Cu.

[0102] Moreover, the metallic fine particles may be comprised of two ormore light-to-heat converting substances by mixing fine particles ofmetals having a low melting point, e.g., Re, Sb, Te, Au, Ag, Cu, Ge, Pband Sn, and fine particles of self-exothermic metals, e.g., Ti, Cr, Fe,Co, Ni, W and Ge. It is also preferred to use metallic fine pieces bycombining fine pieces of metals showing large light absorptionespecially in the form of pieces, e.g., Ag, Pt and Pd, with othermetallic fine pieces.

[0103] The fine particles of the above-described simple substances ofmetals or metal alloys can exhibit the effect of the present inventionby undergoing surface hydrophilizing treatment. As the means of thesurface hydrophilizing treatment, a method of surface treatment with acompound which is hydrophilic and adsorptive to particles, e.g., asurfactant; a method of surface treatment with a substance having ahydrophilic group reactive with the constitutional substances of theparticles; and a method of providing a hydrophilic high polymer having aprotective colloidal property can be used in the present invention. Anespecially preferred method is a surface treatment method with silicate.For example, in the case where the fine particles are iron fineparticles, the surfaces of the particles can be sufficientlyhydrophilized by immersing the particles in a 3% aqueous solution ofsodium silicate at 70° C. for 30 seconds. The surface silicate treatmentof other metallic fine particles can be effected by the similar methods.

[0104] The particle size of these fine particles is preferably 10 μm orless, more preferably from 0.003 to 5 μm, and particularly preferablyfrom 0.01 to 3 μm. Good sensitivity can be obtained with this range ofparticle size.

[0105] When these metallic fine particles are used as infraredray-absorbing dyes in the present invention, the addition amount ispreferably 10 wt % or more, more preferably 20 wt % or more, andparticularly preferably 30 wt % or more, based on the solid contents ofthe image-forming layer. High sensitivity can be obtained with thisrange of the addition amount.

[0106] In the image-forming layer according to the present invention,the dye having large absorption in the visible light region can be usedas the colorant of the image for increasing the discriminability of theimage domain and the non-image domain after image formation.Specifically, Oil Yellow#101, Oil Yellow #103, Oil Pink #312, Oil GreenBG, Oil Blue BOS, Oil Blue #603, Oil Black BY, Oil Black BS, Oil BlackT-505 (products of Orient Kagaku Kogyo Co., Ltd.), Victoria Pure Blue,Crystal Violet (C. I. 42555), Methyl Violet (C.I. 42535), Ethyl Violet,Rhodamine B (C.I. 145170B), Malachite Green (C.I. 42000), and MethyleneBlue (C.I. 52015) can be exemplified. Further, dyes disclosed inJP-A-62-293247 are particularly preferably used. Further, pigments suchas phthalocyanine pigments, azo pigments and titanium oxides can also bepreferably used. The addition amount is preferably from 0.01 to 10 wt %based on the total solid contents of the image-forming layer coatingsolution.

[0107] Moreover, plasticizers can be added to the image-forming layerfor improving the flexibility of the coating film, e.g., polyethyleneglycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexylphthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate,trioctyl phosphate, and tetrahydrofuzfuryl oleate can be used.

[0108] The above-described each component of the image-forming layeraccording to the present invention is dissolved or dispersed in asolvent to prepare a coating solution and coated on a support. Examplesof solvents used here include ethylene dichloride, cyclohexanone, methylethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethylether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propylacetate, dimethoxyethane, methyl lactate, ethyl lactate,N,N-dimethylacetamide, N,N-dimethylformamide, tetramethylurea,N-methylpyrrolidone, dimethyl sulfoxide, sulforan, γ-butyrolactone,toluene, etc., but solvents are not limited thereto. These solvents areused alone or as mixture. The concentration of the solid contents of thecoating solution is preferably from 1 to 50 wt %.

[0109] The coating amount of the image-forming layer on the supportobtained after coating and drying (solid contents) is varied accordingto purposes, but it is generally preferably from 0.5 to 5.0 g/m².Various coating methods can be used, e.g., bar coating, rotary coating,spray coating, curtain coating, dip coating, air knife coating, bladecoating, and roll coating can be used.

[0110] Surfactants, e.g., the fluorine surfactants disclosed inJP-A-62-170950, can be added to the coating solution of theimage-forming layer in the present invention with a view to improvingthe coating property. Addition amount of surfactants is preferably from0.01 to 1 wt %, more preferably from 0.05 to 0.5 wt %, based on theentire solid contents of the image-forming layer.

[0111] Overcoat Layer

[0112] A water-soluble overcoat layer may be provided on theimage-forming layer of the lithographic printing plate precursor of thepresent invention for preventing the image-forming layer surface frombeing stained with lipophilic substances. The water-soluble overcoatlayer for use in the present invention can be easily removed at printingand contains a resin selected from water-soluble organic high molecularweight compounds. The water-soluble organic high molecular weightcompounds should have film-forming property by coating and drying. Thespecific examples of the water-soluble organic high molecular compoundsinclude polyvinyl acetate (having hydrolysis rate of 65% or more),polyacrylic acid and alkali metal salts or amine salts of the same,polyacrylic acid copolymers and alkali metal salts or amine salts of thesame, polymethacrylic acid and alkali metal salts or amine salts of thesame, polymethacrylic acid copolymers and alkali metal salts or aminesalts of the same, polyacrylamide and copolymers of the same,polyhydroxyethyl acrylate, polyvinyl pyrrolidone and copolymers of thesame, polyvinyl methyl ether, vinyl methyl ether/maleic anhydridecopolymers, poly-2-acrylamide-2-methyl-1-propanesulfonic acid and alkalimetal salts or amine salts of the same,poly-2-acrylamide-2-methyl-1-propanesulfonic acid copolymers and alkalimetal salts or amine salts of the same, gum arabic, cellulosederivatives (e.g., carboxymethyl cellulose, carboxyethyl cellulose,methyl cellulose, etc.) and modified products of the same, whitedextrin, plluran, and enzyme-decomposed etherified dextrin. These resinsmay be used as mixture of two or more kinds according to purposes.

[0113] In addition, the overcoat layer may contain the above-describedwater-soluble infrared ray-absorbing dyes. Further, the overcoat layermay contain nonionic surfactants, e.g., polyoxyethylene nonylphenylether and polyoxyethylene dodecyl ether for the purpose of ensuringcoating uniformity when the aqueous solution is coated.

[0114] The dry coating amount of the overcoat layer is preferably from0.1 to 2.0 g/m². The on-press developing property is not impaired andstaining of the image-forming layer surface with lipophilic substancessuch as the adhesion of finger prints is prevented with this range ofthe dry coating amount.

[0115] Support

[0116] The supports of the lithographic printing plate precursor of thepresent invention on which are the above-described image-forming layercan be coated are plate-like materials having dimensional stability. Forexample, paper, paper laminated with plastics (e.g., polyethylene,polypropylene, polystyrene, etc.), metal plates (e.g., aluminum, zinc,copper, etc.), plastic films (e.g., cellulose diacetate, cellulosetriacetate, cellulose propionate, cellulose butyrate, cellulose acetatebutyrate, cellulose nitrate, polyethylene terephthalate, polyethylene,polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), andpaper and plastic films laminated or deposited with the above metals canbe exemplified as the materials of the support. Preferred support is apolyester film or an aluminum plate.

[0117] The aluminum plates are a pure aluminum plate and an aluminumalloy plate comprising aluminum as a main component and a trace amountof foreign elements, or an aluminum or aluminum alloy plate laminatedwith plastics may also be used. Different elements which may becontained in aluminum alloy are silicon, iron, manganese, copper,magnesium, chromium, zinc, bismuth, nickel, titanium, etc. The contentof foreign elements in the aluminum alloy is about 10% by weight orless. (Hereinafter, aluminum and aluminum alloy are generally referredto as “aluminum” and the sheets or plates of the same are referred to as“aluminum sheets”.) Further, an aluminum plate may be produced from analuminum ingot by DC casting or an aluminum ingot by continuous casting.Well-known aluminum plates so far been used can be arbitrarily used inthe present invention.

[0118] The above-described supports for use in the present inventionhave a thickness of from 0.05 to 0.6 mm, preferably from 0.1 to 0.4 mm,and particularly preferably from 0.15 to 0.3 mm.

[0119] It is preferred to subject an aluminum plate to surfaceroughening and surface treatment such as anodization before use. By thesurface treatment, a hydrophilic property is improved and the adhesionwith the image-forming layer can be improved.

[0120] The surface-roughening treatment of the surface of an aluminumplate can be performed by various methods, e.g., mechanicalsurface-roughening treatment, electrochemical roughening by dissolvingthe surface, and chemical roughening by selectively dissolving thesurface. As mechanical roughening, well-known methods, e.g., a ballrubbing method, a brush abrading method, a blasting method, or a buffingmethod, can be used. As chemical roughening, a method of roughening thesurface by immersing an aluminum plate in a saturated aqueous solutionof the aluminum salt of a mineral acid as disclosed in JP-A-54-31187 issuitable. As electrochemical roughening, a method of surface-rougheningin an electrolyte containing an acid such as a hydrochloric acid or anitric acid by alternating current or direct current can be used.Further, electrolytic surface roughening using mixed acids can be usedas disclosed in JP-A-54-63902.

[0121] These surface roughening treatments are preferably performed sothat the center line average surface roughness (Ra) of the surface of analuminum plate becomes from 0.2 to 1.0 μm.

[0122] The thus surface-roughened aluminum plate is, if required,subjected to alkali etching treatment with an aqueous solution ofpotassium hydroxide or sodium hydroxide and neutralizing treatment andthen to anodizing treatment to increase the abrasion resistance of thesurface.

[0123] Various electrolytes for forming porous oxide film can be used inthe anodizing treatment of an aluminum plate and, in general, sulfuricacid, hydrochloric acid, oxalic acid, chromic acid and mixed acids ofthese are used. The concentration of these electrolytes are arbitrarilydetermined according to the kinds of electrolytes.

[0124] Anodizing treatment conditions vary according to electrolytesused but in general the appropriate concentration of electrolyte is from1 to 80 wt % solution, the liquid temperature is from 5 to 70° C., theelectric current density is from 5 to 60 A/dm², the voltage is from 1 to100 V, electrolytic time is from 10 seconds to 5 minutes.

[0125] The amount of the oxide film formed is preferably from 1.0 to 5.0g/m², particularly preferably from 1.5 to 4.0 g/m².

[0126] The support surface-treated and having an anodic oxidation layeras described above may be used as it is, but micro-pore enlargingtreatment of an anodic oxidation layer, sealing treatment ofmicro-pores, and surface hydrophilizing treatment of immersing thesupport in an aqueous solution containing a hydrophilic compound asdisclosed in Japanese Patent Application Nos. 2000-65219 and 2000-1433B7may be performed arbitrarily for further improving adhering propertieswith the upper layer, hydrophilic properties, staining resistance andheat insulating properties, if necessary.

[0127] As the preferred hydrophilic compounds for the abovehydrophilizing treatment, polyvinyl phosphonic acid, compounds having asulfonic acid group, saccharide compounds, citric acid, alkali metalsilicate, potassium zirconium fluoride, phosphate/inorganic fluorinecompounds can be used in the present invention.

[0128] When a support, such as a polyester film, the surface of which isnot sufficiently hydrophilic, is used as the support in the presentinvention, it is preferred to coat a hydrophilic layer to make thesurface hydrophilic. A hydrophilic layer formed by coating a coatingsolution containing a colloidal oxide or hydroxide of at least oneelement selected from beryllium, magnesium, aluminum, silicon, titanium,boron, germanium, tin, zirconium, iron, vanadium, antimony andtransition metals as disclosed in Japanese Patent Application No.2000-10810 is preferred. A hydrophilic layer formed by coating a coatingsolution containing a colloidal oxide or hydroxide of silicon ispreferred above all.

[0129] In the present invention, an inorganic undercoat layer containinga water-soluble metal salt, e.g., zinc borate, or an organic undercoatlayer containing carboxymethyl cellulose, dextrin, or polyacrylic acidas disclosed in Japanese Patent Application No. 2000-143387 may beprovided before coating an image-forming layer, if necessary.

[0130] This undercoat layer may contain the above-described infraredray-absorbing dyes.

[0131] Plate-Making and Printing

[0132] An image is formed by heating on a lithographic printing plateprecursor in the present invention. Specifically, an image is recordedby direct imagewise recording with a thermal recording head, scanningexposure with an infrared laser, high intensity flash exposure by axenon discharge lamp, etc., and infrared lamp exposure. Exposure bysolid state high output infrared lasers such as semiconductor lasersemitting infrared rays of wavelength of from 700 to 12,000 nm and YAGlasers is preferred in the present invention.

[0133] An image-exposed lithographic printing plate precursor accordingto the present invention can be loaded on a printing machine withoutrequiring any further process, and printing can be performed using inkand a fountain solution by an ordinary procedure.

[0134] The lithographic printing plate precursor according to thepresent invention can also be subjected to exposure after being mountedon a plate cylinder by the laser installed on a printing machine, andthen on-press development with a fountain solution and/or an ink, asdisclosed in Japanese patent 2938398.

[0135] The lithographic printing plate precursor according to thepresent invention can also be used in printing after development withwater or an aqueous solution as a developing solution.

EXAMPLE

[0136] The present invention will be illustrated in more detail withreference to examples below, but these are not to be construed aslimiting the invention.

Synthesis Example of Fine Particles (11)

[0137] As oil phase components, 6.0 g of exemplified Polymer P-2 (aweight average molecular weight: 3,000), 1.5 g of an infraredray-absorbing dye (exemplified Compound IR-26), 0.5 g of an acidprecursor (exemplified Compound AL-14), and 0.1 g of an anionicsurfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) weredissolved in 18.0 g of ethyl acetate, and the solution was mixed with36.0 g of a 4% aqueous solution of polyvinyl alcohol (PVA205,manufactured by Kuraray Co., Ltd.) of a water phase component. The mixedsolution was emulsified and dispersed with a homogenizer at 10,000 rpmfor 10 minutes, then 24 g of water was added thereto, and the ethylacetate was evaporated with stirring the mixed solution at 60° C. for 90minutes. The concentration of the solid content of the thus-obtainedfine particle dispersion solution was 13.0 wt % and the average particlesize was 0.33 μm.

Synthesis Example of Fine Particles (12)

[0138] As oil phase components, 3.0 g of a bifunctional vinyloxycompound (exemplified Compound M-1), 3.0 g of a benzylmethacrylate/2-hydroxymethyl methacrylate/methacrylic acid copolymer ina copolymerization ratio of 60/20/20 (a weight average molecular weight:30,000), 1.5 g of an infrared ray-absorbing dye (exemplified CompoundIR-26), 0.5 g of an acid precursor (exemplified Compound A1-14), and 0.1g of Pionin A-41C were dissolved in 18.0 g of ethyl acetate, and thesolution was mixed with 36.0 g of a 4% aqueous solution of PVA205 of awater phase component. The mixed solution was emulsified and dispersedwith a homogenizer at 10,000 rpm for 10 minutes, then 24 g of water wasadded thereto, and the ethyl acetate was evaporated with stirring themixed solution at 60° C. for 90 minutes. The concentration of the solidcontent of the thus-obtained fine particle dispersion solution was 13.5wt % and the average particle size was. 0.19 μm.

Synthesis Example of Fine Particles (13) Acid Precursor Was notContained in Fine Particles

[0139] A fine particle dispersion solution was synthesized in the samemanner as in the synthesis example of fine particles (12) except thatthe acid precursor was not added. The concentration of the solid contentof the thus-obtained fine particle dispersion solution was 13.5 wt % andthe average particle size was 0.25 μm.

Synthesis Example of Fine Particles (14) Infrared Ray-Absorbing Dye Wasnot Contained in Fine Particles

[0140] A fine particle dispersion solution was synthesized in the samemanner as in the synthesis example of fine particles (12) except thatthe infrared ray-absorbing dye was not added. The concentration of thesolid content of the thus-obtained fine particle dispersion solution was13.5 wt % and the average particle size was 0.30 μm.

Synthesis Example of Fine Particles (i) for Comparison Vinyloxy CompoundWas not Contained in Fine Particles

[0141] As oil phase components, 6.0 g of an allyl methacrylate/methylmethacrylate copolymer (copolymerization molar ratio: 70/30, a weightaverage molecular weight: 15,000), 1.5 g of an infrared ray-absorbingdye (exemplified Compound IR-26), 0.5 g of an acid precursor(exemplified Compound A1-14), and 0.1 g of Pionin A-41C were dissolvedin 18.0 g of ethylacetate, and the solution was mixed with 36.0 g of a4% aqueous solution of PVA205 of a water phase component. The mixedsolution was emulsified and dispersed with a homogenizer at 10,000 rpmfor 10 minutes, then 24 g of water was added thereto, and the ethylacetate was evaporated with stirring the mixed solution at 60° C. for 90minutes. The concentration of the solid content of the thus-obtainedfine particle dispersion solution was 13.5 wt % and the average particlesize was 0.2 μm.

Synthesis Example of Fine Particles (21)

[0142] As oil phase components, 6.0 g of Epikote 1004 (manufactured byYuka Shell Epoxy Co., Ltd.), 1.5 g of an infrared ray-absorbing dye(exemplified Compound IR-26), 0.5 g of an acid precursor (exemplifiedCompound A2-10), and 0.1 g of an anionic surfactant Pionin A-41C(manufactured by Takemoto Yushi Co., Ltd.) were dissolved in 18.0 g ofethyl acetate, and the solution was mixed with 36.0 g of a 4% aqueoussolution of polyvinyl alcohol (PVA205, manufactured by Kuraray Co.,Ltd.) of a water phase component. The mixed solution was emulsified anddispersed with a homogenizer at 10,000 rpm for 10 minutes, then 24 g ofwater was added thereto, and the ethyl acetate was evaporated withstirring the mixed solution at 60° C. for 90 minutes. The concentrationof the solid content of the thus-obtained fine particle dispersionsolution was 12.5 wt % and the average particle size was 0.22 μm.

Synthesis Example of Fine Particles (22)

[0143] As oil phase components, 3.0 g of bisphenol A diglycidyl ether,3.0 g of a benzyl methacrylate/2-hydroxymethyl methacrylate/methacrylicacid copolymer in a copolymerization ratio of 60/20/20 (a weight averagemolecular weight: 30,000), 1.5 g of an infrared ray-absorbing dye(exemplified Compound IR-26), 0.5 g of an acid precursor (exemplifiedCompound A2-10), and 0.1 g of Pionin A-41C were dissolved in 18.0 g ofethylacetate, and the solution was mixed with 36.0 g of a 4% aqueoussolution of PVA205 of a water phase component. The mixed solution wasemulsified and dispersed with a homogenizer at 10,000 rpm for 10minutes, then 24 g of water was added thereto, and the ethyl acetate wasevaporated with stirring the mixed solution at 60° C. for 90 minutes.The concentration of the solid content of the thus-obtained fineparticle dispersion solution was 13.0 wt % and the average particle sizewas 0.18 μm.

Synthesis Example of Fine Particles (23) Acid Precursor Was notContained in Fine Particles

[0144] A fine particle dispersion solution was synthesized in the samemanner as in the synthesis example of fine particles (22) except thatthe acid precursor was not added. The concentration of the solid contentof the thus-obtained fine particle dispersion solution was 13.5 wt % andthe average particle size was 0.25 μm.

Synthesis Example of Fine Particles (24) Infrared Ray-Absorbing Dye Wasnot Contained in Fine Particles

[0145] A fine particle dispersion solution was synthesized in the samemanner as in the synthesis example of fine particles (22) except thatthe infrared ray-absorbing dye was not added. The concentration of thesolid content of the thus-obtained fine particle dispersion solution was13.5 wt % and the average particle size was 0.30 μm.

Synthesis Example of Fine Particles (25)

[0146] A fine particle dispersion solution was synthesized in the samemanner as in the synthesis example of fine particles (21) except thatacid precursor A2-10 was replaced with A2-6. The concentration of thesolid content of the thus-obtained fine particle dispersion solution was13.5 wt % and the average particle size was 0.32 μm.

Synthesis Example of Fine Particles (ii) for Comparison Epoxy CompoundWas not Contained in Fine Particles

[0147] As oil phase components, 6.0 g of an allyl methacrylate/methylmethacrylate copolymer (copolymerization molar ratio: 70/30, a weightaverage molecular weight: 15,000), 1.5 g of an infrared ray-absorbingdye (exemplified Compound IR-26), 0.5 g of an acid precursor(exemplified Compound A2-14), and 0.1 g of Pionin A-41C were dissolvedin 18.0 g of ethylacetate, and the solution was mixed with 36.0 g of a4% aqueous solution of PVA205 of a water phase component. The mixedsolution was emulsified and dispersed with a homogenizer at 10,000 rpmfor 10 minutes, then 24 g of water was added thereto, and the ethylacetate was evaporated with stirring the mixed solution at 60° C. for 90minutes. The concentration of the solid content of the thus-obtainedfine particle dispersion solution was 13.5 wt % and the average particlesize was 0.2 μm.

Synthesis Example of Fine Particles (31)

[0148] Six point zero (6.0) grams of a phenolic resol resin having aweight average molecular weight of 2,000, 1.5 g of an infraredray-absorbing dye (exemplified Compound IR-26), and 0.1 g of an anionicsurfactant Pionin A-41C (manufactured by Takemoto Yushi Co., Ltd.) weredissolved in 21.0 g of ethyl acetate to form an oil phase, and thesolution was mixed with 36.0 g of a 4% aqueous solution of polyvinylalcohol (PVA205, manufactured by Kuraray Co., Ltd.) of a water phasecomponent. The mixed solution was emulsified and dispersed with ahomogenizer at 10,000 rpm for 10 minutes, then 24.0 g of water was addedthereto, and the organic solvent was evaporated with heating the mixedsolution at 50° C. for 3 hours. The concentration of the solid contentof the thus-obtained fine particle dispersion solution was 15.0 wt % andthe average particle size was 0.7 μm.

Synthesis Example of Fine Particles (32)

[0149] Six point zero (6.0) grams of an epoxy resin Epikote 1002(manufactured by Yuka Shell Epoxy Co., Ltd.), 0.5 g of1,8-diaminooctane, 1.5 g of an infrared ray-absorbing dye (exemplifiedCompound IR-26), and 0.1 g of Pionin A-41C (manufactured by TakemotoYushi Co., Ltd.) were dissolved in 5.0 g of acetonitrile and 16.0 g ofethyl acetate to form an oil phase. A fine particle dispersion solutionwas synthesized in the same manner as in the synthesis example of fineparticles (31) hereafter. The concentration of the solid content of thethus-obtained fine particle dispersion solution was 14.0 wt % and theaverage particle size was 0.4 μm.

Synthesis Example of Fine Particles (33)

[0150] Six point zero (6.0) grams of a phenol novolak resin having aweight average molecular weight of 7,000, 1.0 g of a low molecularweight thermosetting compound (a compound represented by formula (T-1)),1.0 g of an infrared ray-absorbing dye (exemplified Compound IR-26), and0.1 g of Pionin A-41C were dissolved in 21.0 g of ethyl acetate to forman oil phase. A fine particle dispersion solution was synthesized in thesame manner as in the synthesis example of fine particles (31)hereafter. The concentration of the solid content of the thus-obtainedfine particle dispersion solution was 15.0 wt % and the average particlesize was 0.7 μm.

Synthesis Example of Fine Particles (34)

[0151] Six point zero (6.0) grams of a cresol novolak resin ofpolymerization ratio of m-/p- of 6/4 having a weight average molecularweight of 4,000, 1.0 g of hexamethoxymethylmelamine, 1.5 g of aninfrared ray-absorbing dye (exemplified Compound IR-26), and 0.1 g ofPionin A-41C were dissolved in 10.0 g of acetonitrile and 11.0 g ofethyl acetate to form an oil phase. The same water phase as used in thesynthesis example of fine particles (31) was added to the above solutionand the mixture was emulsified with a homogenizer in the same manner asabove, then 24.0 g of water was added to the emulsion, and then theorganic solvent was evaporated with heating the emulsion at 60° C. for 3hours. The concentration of the solid content of the thus-obtained fineparticle dispersion solution was 20.0 wt % and the average particle sizewas 0.8 μm.

Synthesis Example of Fine Particles (35)

[0152] Six point zero (6.0) grams of a 100% oil-soluble phenolic resin(pp-3120, manufactured by Gun-ei Kagaku Kogyo Co., Ltd.), 1.5 g of aninfrared ray-absorbing dye (exemplified Compound IR-26), and 0.1 g ofPionin A-41C were dissolved in 5.0 g of acetonitrile and 16.0 g of ethylacetate to form an oil phase. A fine particle dispersion solution wassynthesized in the same manner as in the synthesis example of fineparticles (31) hereafter. The concentration of the solid content of thethus-obtained fine particle dispersion solution was 14.5 wt % and theaverage particle size was 0.9 μm.

Synthesis Example of Fine Particles (36)

[0153] Six point zero (6.0) grams of a phenolic resol resin having aweight average molecular weight of 2,000 and 0.1 g of Pionin A-41C weredissolved in 21.0 g of ethyl acetate to form an oil phase. A fineparticle dispersion solution was synthesized in the same manner as inthe synthesis example of fine particles (31) hereafter. Theconcentration of the solid content of the thus-obtained fine particledispersion solution was 15.0 wt % and the average particle size was 0.7μm.

Synthesis Example of Fine Particles (iii) for Comparison ThermosettingCompound Was not Contained in Fine Particles

[0154] Six point zero (6.0) grams of a polystyrene resin having a weightaverage molecular weight of 10,000, 1.5 g of an infrared ray-absorbingdye (exemplified Compound IR-26), and 0.1 g of Pionin A-41C weredissolved in 21.0 g of ethyl acetate to form an oil phase. A fineparticle dispersion solution was synthesized in the same manner as inthe synthesis example of fine particles (31) hereafter. Theconcentration of the solid content of the thus-obtained fine particledispersion solution was 15.0 wt % and the average particle size was 0.7μm.

Synthesis Example of Microcapsules (11)

[0155] As oil phase components, 40 g of the adduct of trimethylolpropaneand xylylene diisocyanate (Takenate D-110N, a microcapsule wallmaterial, manufactured by Takeda Chemical Industries Ltd.), 10 g of abifunctional vinyloxy compound (exemplified Compound M-15), 10 g of apolymer having a vinyloxy group (exemplified Compound P-6), 1.5 g of aninfrared ray-absorbing dye (exemplified Compound IR-26), 0.5 g of anacid precursor (exemplified Compound A1-8), and 0.1 g of Pionin A-41Cwere dissolved in 60 g of ethyl acetate. As a water phase component, 120g of a 4% aqueous solution of PVA205 was prepared. The thus-obtained oilphase components and the water phase component were emulsified with ahomogenizer at 10,000 rpm for 10 minutes, then 40 g of water was addedthereto, and the solution was stirred at room temperature for 30 minutesand further at 40° C. for 3 hours. The concentration of the solidcontent of the thus-obtained microcapsule solution was 25 wt % and theaverage particle size was 0.5 μm.

Synthesis Example of Microcapsules (12)

[0156] As oil phase components, 40 g of Takenate D-110N, 10 g of abifunctional vinyloxy compound (exemplified Compound M-15), 10 g of apolymer having a vinyloxy group (exemplified Compound P-6, a weightaverage molecular weight: 20,000), 10 g of poly-p-hydroxystyrene (aweight average molecular weight: 2,300), 1.5 g of an infraredray-absorbing dye (exemplified Compound IR-26), 0.5 g of an acidprecursor (exemplified Compound A1-8), and 0.1 g of Pionin A-41C weredissolved in 60 g of ethyl acetate. As a water phase component, 120 g ofa 4% aqueous solution of PVA205 was prepared. The thus-obtained oilphase components and the water phase component were emulsified with ahomogenizer at 10,000 rpm for 10 minutes, then 40 g of water was addedthereto, and the solution was stirred at room temperature for 30 minutesand further at 40° C. for 3 hours. The concentration of the solidcontent of the thus-obtained microcapsule solution was 30 wt % and theaverage particle size was 0.5 μm.

Synthesis Example of Microcapsules (i) for Comparison Vinyloxy CompoundWas not Contained in Microcapsules

[0157] As oil phase components, 40 g of Takenate D-110N, 10 g oftrimethylolpropane diacrylate, 10 g of a copolymer of allyl methacrylateand butyl methacrylate (molar ratio: 60/40), 1.5 g of an infraredray-absorbing dye (exemplified Compound IR-26), 0.5 g of an acidprecursor (exemplified Compound A1-8), and 0.1 g of Pionin A-41C weredissolved in 60 g of ethyl acetate. As a water phase component, 120 g ofa 4% aqueous solution of PVA205 was prepared. The thus-obtained oilphase components and the water phase component were emulsified with ahomogenizer at 10,000 rpm for 10 minutes, then 40 g of water was addedthereto, and the solution was stirred at room temperature for 30 minutesand further at 40° C. for 3 hours. The concentration of the solidcontent of the thus-obtained microcapsule solution was 27 wt % and theaverage particle size was 0.5 μm.

Synthesis Example of Microcapsules (21)

[0158] As oil phase components, 40 g of the adduct of trimethylolpropaneand xylylene diisocyanate (Takenate D-110N, a microcapsule wallmaterial, manufactured by Takeda Chemical Industries Ltd.), 10 g of abifunctional epoxy compound (exemplified Compound M-15), 10 g ofSumiepoxy ESCN-195XHH (a novolak type epoxy resin manufactured bySumitomo Chemical Co., Ltd.), 1.5 g of an infrared ray-absorbing dye(exemplified Compound IR-26), 0.5 g of an acid precursor (exemplifiedCompound A2-10), and 0.1 g of Pionin A-41C were dissolved in 60 g ofethyl acetate. As a water phase component, 120 g of a 4% aqueoussolution of PVA205 was prepared. The thus-obtained oil phase componentsand the water phase component were emulsified with a homogenizer at10,000 rpm for 10 minutes, then 40 g of water was added thereto, and thesolution was stirred at room temperature for 30 minutes and further at40° C. for 3 hours. The concentration of the solid content of thethus-obtained microcapsule solution was 23.0 wt % and the averageparticle size was 0.35 μm.

Synthesis Example of Microcapsules (22)

[0159] As oil phase components, 40 g of Takenate D-110N, 10 g ofresorcin diglycidyl ether, 10 g of a methyl methacrylate/glycidylmethacrylate copolymer (copolymerization molar ratio: 50/50, a weightaverage molecular weight: 20,000), 10 g of poly-p-hydroxystyrene (aweight average molecular weight: 2,300), 1.5 g of an infraredray-absorbing dye (exemplified Compound IR-26), 0.5 g of an acidprecursor (exemplified Compound A2-10), and 0.1 g of Pionin A-41C weredissolved in 60 g of ethyl acetate. As a water phase component, 120 g ofa 4% aqueous solution of PVA205 was prepared. The thus-obtained oilphase components and the water phase component were emulsified with ahomogenizer at 10,000 rpm for 10 minutes, then 40 g of water was addedthereto, and the solution was stirred at room temperature for 30 minutesand further at 40° C. for 3 hours. The concentration of the solidcontent of the thus-obtained microcapsule solution was 25.0 wt % and theaverage particle size was 0.30 μm.

Synthesis Example of Microcapsules (23)

[0160] A fine particle dispersion solution was synthesized in the samemanner as in the synthesis of microcapsules (22) except that acidprecursor A2-10 was replaced with A2-6. The concentration of the solidcontent of the thus-obtained microcapsule solution was 28.5 wt % and theaverage particle size was 0.40 μm.

Synthesis Example of Microcapsules (ii) for Comparison Epoxy CompoundWas not Contained in Microcapsules

[0161] As oil phase components, 40 g of Takenate D-110N, 10 g oftrimethylolpropane diacrylate, 10 g of a copolymer of allyl methacrylateand butyl methacrylate (molar ratio: 60/40), 1.5 g of an infraredray-absorbing dye (exemplified Compound IR-26), 0.5 g of an acidprecursor (exemplified Compound A-10), and 0.1 g of Pionin A-41C weredissolved in 60 g of ethyl acetate. As a water phase component, 120 g ofa 4% aqueous solution of PVA205 was prepared. The thus-obtained oilphase components and the water phase component were emulsified with ahomogenizer at 10,000 rpm for 10 minutes, then 40 g of water was addedthereto, and the solution was stirred at room temperature for 30 minutesand further at 40° C. for 3 hours. The concentration of the solidcontent of the thus-obtained microcapsule solution was 27 wt % and theaverage particle size was 0.5 μm.

Examples I-1 to I-10 and Comparative Examples I-1 to I-4

[0162] A lithographic printing plate precursor was produced by coatingeach of the image-forming layer coating solutions (1) to (3) having thecomposition shown below on support (A) in the following preparationexample by bar coating, each of the coated supports was dried in an ovenat 80° C. for 90 seconds, thus each lithographic printing plateprecursor having a dry coating amount of the image-forming layer of 1.0g/m² was produced. Each coating solution used is shown in Table 1 below.

Preparation Example of Support (A)

[0163] The molten metal of JIS A1050 alloy containing 99.5% or more ofaluminum, 0.30% of Fe, 0.10% of Si, 0.02% of Ti and 0.013% of Cu wassubjected to purification treatment and casting. In the purificationtreatment, degassing treatment for eliminating unnecessary gases in themolten metal, such as hydrogen, and ceramic tube filter treatment werecarried out. Casting was performed by DC casting method. The solidifiedingot having a thickness of 500 mm underwent scalping in a thickness of10 mm from the surface and homogenizing treatment was performed at 550°C. for 10 hours so that the intermetallic compound was not coarsened. Inthe next place, the plate was subjected to hot rolling at 400° C., thenintermediate-annealing in a continuous annealing furnace at 500° C. for60 seconds, and then cold rolling, to thereby produce an aluminum rolledplate having a thickness of 0.30 mm. The center line average surfaceroughness (Ra) (defined in JIS B 0601) of the aluminum plate surfaceafter cold rolling was controlled to become 0.2 μm by controlling theroughness of pressure roll. The plate was then applied to a tensionleveller for improving a flatness.

[0164] The plate was surface-treated to obtain a lithographic printingplate support.

[0165] In the first place, the aluminum plate was degreased with a 10%aqueous solution of sodium aluminate at 50° C. for 30 seconds toeliminate the rolling oil on the surface of the plate, neutralized in a30% aqueous solution of sulfuric acid at 50° C. for 30 seconds, and thensubjected to desmutting treatment.

[0166] In the next place, the surface of the support was subjected tograining treatment, i.e., surface roughening treatment, for improvingadhering property of the support and the image-forming layer and givingwater retentivity to the non-image domain. An aqueous solutioncontaining 1% of nitric acid and 0.5% of aluminum nitrate was maintainedat 45° C., and under the condition of electric current density of 20A/dm² by indirect electric power supplying cell, the plate was subjectedto electrolytic graining by supplying the quantity of electricity ofanode of of anode of 240 C/dm², using alternating waveform of duty ratioof 1/1 with conveying the aluminum web in the aqueous solution.Subsequently, the plate underwent etching in a 10% sodium aluminateaqueous solution at 50° C. for 30 seconds, neutralization in a 30%sulfuric acid aqueous solution at 50° C. for 30 seconds, and thendesmutting treatment.

[0167] Further, for improving abrasion resistance, chemical resistanceand water retentivity, an oxide film was formed on the support byanodization. A20% sulfuric acid aqueous solution was used as theelectrolyte at 35° C. An anodic oxidation layer of 2.5 g/m² was formedby the electrolytic treatment with direct current of 14 A/dm² byindirect electric power supplying cell with conveying the aluminum webthrough the electrolyte.

[0168] Silicate treatment was performed for ensuring hydrophilicproperties as the non-image domain of the printing plate hereafter. A1.5% aqueous solution of sodium silicate No. 3 (i.e., disodiumtrisilicate) was maintained at 70° C. and the aluminum web was conveyedso that the contact time of the aluminum web with the aqueous solutionbecame 15 seconds and the web was further washed with water. The adheredamount of Si was 10 mg/m². The center line average surface roughness(Ra) of the surface of the thus-obtained support (A) was 0.25 μm.Image-Forming Layer Coating Solution (1) Water 100 g Fine particles ormicrocapsules 5 g (in terms of solid content) Hydrophilic resin (shownin Table 1) 0.5 g Image-Forming Layer Coating Solution (2) (an infraredray-absorbing dye was contained in the matrix of the image-forminglayer) Water 100 g Fine particles or microcapsules 5 g (in terms ofsolid content) Hydrophilic resin (shown in Table 1) 0.5 g An infraredray-absorbing dye 0.5 g (exemplified Compound IR-11) Image-Forming LayerCoating Solution (3) (an acid precursor was contained in the matrix ofthe image-forming layer) Water 100 g Fine particles or microcapsules 5 g(in terms of solid content) Hydrophilic resin (shown in Table 1) 0.5 gAcid precursor (exemplified Compound A1-17) 0.5 g

[0169] The thus-obtained lithographic printing plate precursor wassubjected to exposure using Trendsetter mounting a water-cooling type 40W infrared semiconductor laser manufactured by Creo Co., Ltd., under theconditions of output of 9 W, external drum rotating speed of 210 rpm,printing plate surface energy of 100 mJ/M², and resolution of 2,400 dpi.The exposed precursor was mounted on the cylinder of a printing machineSOR-M (manufactured by Heiderberg Co.) without further developingtreatment, and printing was performed after feeding a fountain solution,then an ink, and then printing paper.

[0170] As a result, on-press development and printing were effected withevery printing plate precursor with no problem. The printable number ofsheets is shown in Table 1 below. TABLE 1 Examples I-1 to I-10 andComparative Examples I-1 to I-4 Kind of Image- Forming Layer Kind ofFine Kind of Printable Coating Particles or Hydrophilic Number ofExample No. Solution Microcapsules Resin Sheets Example I-1 (1) Fineparticles (11) PAA 20,000 Example I-2 (1) Fine particles (11) PHEA25,000 Example I-3 (1) Fine particles (11) PVP 15,000 Example I-4 (1)Fine particles (12) PAA 30,000 Example I-5 (3) Fine particles (13) PAA15,000 Example I-6 (2) Fine particles (14) PAA 15,000 Example I-7 (1)Microcapsule (11) PAA 25,000 Example I-8 (1) Microcapsule (11) PHEA25,000 Example I-9 (1) Microcapsule (11) PVP 20,000 Example I-10 (1)Microcapsule (12) PAA 35,000 Comparative (1) Fine particles (i) PAA10,000 Example I-1 Comparative (1) Fine particles (i) PVP 8,000 ExampleI-2 Comparative (1) Microcapsules (i) PAA 8,000 Example I-3 Comparative(1) Microcapsules (i) PVP 10,000 Example I-4

[0171] It can be seen from the results in Table 1 that the lithographicprinting plate precursors using the fine particles containing a compoundhaving a vinyl oxy group or the microcapsules containing a compoundhaving a vinyloxy group exhibited high press life (i.e., high printingdurability). Further, the lithographic printing plate precursorscontaining an infrared ray-absorbing dye or an acid precursor in thefine particles or microcapsules exhibited higher press life than thosecontaining the same in the outside of the fine particles ormicrocapsules. Moreover, the lithographic printing plate precursorsusing the hydrophilic resin having a carboxyl group or a hydroxyl groupreacting with a vinyloxy group exhibited higher press life than thoseusing the hydrophilic resin not having these groups.

Examples II-1 to II-10 and Comparative Examples II-1 to II-4

[0172] A lithographic printing plate precursor was produced by coatingeach of the image-forming layer coating solutions (4) to (7) having thecomposition shown below on the same support (A) used in the aboveExamples I by bar coating, the coated support was dried in an oven at80° C. for 90 seconds, thus each lithographic printing plate precursorhaving a dry coating amount of the image-forming layer of 1.0 g/m² wasproduced. The combination of the coating solution is shown in Table 2below. Image-Forming Layer Coating Solution (4) Water 100 g Fineparticles or microcapsules 5 g (in terms of solid content) Hydrophilicresin (shown in Table 2) 0.5 g Image-Forming Layer Coating Solution (5)(an infrared ray-absorbing dye was contained in the matrix of theimage-forming layer) Water 100 g Fine particles or microcapsules 5 g (interms of solid content) Hydrophilic resin (shown in Table 2) 0.5 g Aninfrared ray-absorbing dye 0.5 g (exemplified Compound IR-11)Image-Forming Layer Coating Solution (6) (an acid precursor wascontained in the matrix of the image-forming layer) Water 95 g Methanol5 g Fine particles or microcapsules 5 g (in terms of solid content)Hydrophilic resin (shown in Table 2) 0.5 g Acid precursor (exemplifiedCompound A2-13) 0.5 g Image-Forming Layer Coating Solution (7) Water 85g 1-Methoxy-2-propanol 15 g Microcapsules (in terms of solid content) 5g Hydrophilic resin (shown in Table 2) 0.5 g

[0173] The thus-obtained lithographic printing plate precursor wassubjected to exposure in the same manner as in Examples I and thenprinting was performed. As a result, on-press development and printingwere effected with every printing precursor with no problem. Theprintable number of sheets is shown in Table 2 below. TABLE 2 ExamplesII-1 to II-10 and Comparative Examples II-1 to II-4 Kind of Image-Forming Layer Kind of Fine Kind of Printable Coating Particles orHydrophilic Number of Example No. Solution Microcapsules Resin SheetsExample II-1 (4) Fine particles (21) PAA 25,000 Example II-2 (4) Fineparticles (21) PVP 20,000 Example II-3 (4) Fine particles (22) PAA30,000 Example II-4 (4) Fine particles (23) PAA 15,000 Example II-5 (6)Fine particles (24) PAA 15,000 Example II-6 (5) Fine particles (25) PAA20,000 Example II-7 (7) Microcapsule (21) PAA 20,000 Example II-8 (7)Microcapsule (21) PVP 15,000 Example II-9 (7) Microcapsule (22) PAA25,000 Example II-10 (7) Microcapsule (23) PAA 20,000 Comparative (4)Fine particles (ii) PAA 10,000 Example II-1 Comparative (4) Fineparticles (ii) PVP 8,000 Example II-2 Comparative (7) Microcapsules (ii)PAA 8,000 Example II-3 Comparative (7) Microcapsules (ii) PVP 10,000Example II-4

[0174] It can be seen from the results in Table 2 that the lithographicprinting plate precursors using the fine particles containing a compoundhaving an epoxy group or the microcapsules containing a compound havingan epoxy group exhibited high press life. Further, the lithographicprinting plate precursors containing an infrared ray-absorbing dye or anacid precursor in the fine particles or microcapsules exhibited higherpress life than those containing the same in the outside of the fineparticles or microcapsules. Moreover, the lithographic printing plateprecursors using the hydrophilic resin having a carboxyl group or ahydroxyl group reacting with an epoxy group exhibited higher press lifethan those using the hydrophilic resin not having these groups.

Examples III-1 to III-10 and Comparative Example III-1

[0175] A lithographic printing plate precursor was produced by coatingeach of the image-forming layer coating solutions (8) to (10) having thecomposition shown below on each of the supports prepared in PreparationExamples B1 to B7 by bar coating, each of the coated supports was driedin an oven at 90° C. for 120 seconds, thus each lithographic printingplate precursor having a dry coating amount of the image-forming layerof 1.2 g/m² was produced. The combination of the coating solution andthe support is shown in Table 3 below.

Preparation Example of Support B1

[0176] A rolled plate having a thickness of 0.24 mm of JIS-A-1050aluminum containing 0.01% of copper, 0.03% of titanium, 0.3% of iron,and 0.1% of silicon was surface-grained with a 20 wt % aqueoussuspension of 400 mesh purmice stone powder (manufactured by KyoritsuYogyo Co., Ltd.) and a rotary nylon brush (6,10-nylon) having a (hair)diameter of 0.30 mm, and then the plate was thoroughly washed withwater.

[0177] The plate was immersed in a 15 wt % aqueous solution of sodiumhydroxide (containing 5 wt % of aluminum) and etched so as to reach thedissolving amount of the aluminum of 5 g/m², then washed with flowingwater, followed by neutralization with a 1 wt % aqueous solution ofnitric acid. Subsequently, the plate was subjected to electrolyticsurface roughening treatment in a 0.7 wt % aqueous solution of nitricacid (containing 0.5% of aluminum ions) using rectangular alternatingwave form voltage (electric current ratio r=0.90, electric current waveform disclosed in JP-B-58-5796) of the voltage of 9.3 V at the cathodetime and the voltage of 10.5 V at the anode time, with the quantity ofelectricity of 110 Coulomb/dm² at the anode time. After washing withwater, the plate was immersed in a 10 wt % aqueous solution of sodiumhydroxide at 40° C. and etched so as to reach the dissolving amount ofthe aluminum of 1 g/m², and then washed with water. The plate was thenimmersed in a 30% aqueous solution of sulfuric acid at 50° C.,desmutted, and washed with water.

[0178] Further, the plate was subjected to anodizing treatment in a 20wt % aqueous solution of sulfuric acid (containing 0.8% of aluminumions) at 35° C. using direct current to form a porous anodic oxidationlayer. That is, electrolysis was performed at electric current densityof 13 A/dm², thereby a support having an anodic oxidation layer weightof 4.0 g/m² was obtained by controlling the electrolysis time, and thealuminum support was washed with water and dried.

[0179] The thus-obtained aluminum support had reflection density of 0.28and center line average surface roughness (Ra) of 0.45 μm. Thereflection density was measured by a Macbeth RD920 reflectiondensitometer. (This semi-finished support is hereinafter called “support(B)”.)

[0180] Support (B) was subjected to immersion treatment in a 0.5 wt %aqueous solution of polyvinylsulfonic acid at 60° C. for 10 seconds, andthen washed with water and dried, thereby support (B1) was obtained.

Preparation Example of Support B2

[0181] Support (B) was subjected to immersion treatment in a 0.1 wt %aqueous solution of sodium lignin sulfonate (pH 5.5) at 80° C. for 60seconds, and then washed with water and dried, thereby support (B2) wasobtained.

Preparation Example of Support B3

[0182] Support (B) was subjected to immersion treatment in a 1 wt %aqueous solution of saponin (pH 5.5) at 40° C. for 30 seconds, and thenwashed with water and dried, thereby support (B3) was obtained.

Preparation Example of Support B4

[0183] Support (B) was subjected to immersion treatment in a 5 wt %aqueous solution of citric acid at 50° C. for 60 seconds, and thenwashed with water and dried, thereby support (B4) was obtained.

Preparation Example of Support B5

[0184] Support (B) was subjected to immersion treatment in a 2.5 wt %aqueous solution of sodium silicate at 70° C. for 12 seconds, and thenwashed with water and dried, thereby support (B5) was obtained.

Preparation Example of Support B6

[0185] Support (B) was subjected to immersion treatment in a 1.5 wt %aqueous solution of potassium zirconium fluoride at 60° C. for 60seconds, and then washed with water and dried, thereby support (B6) wasobtained.

Preparation Example of Support B7

[0186] Support (B) was subjected to immersion treatment in an aqueoussolution of NaH₂PO₄/NaF (10 wt %/0.1 wt %) at 70° C. for 30 seconds, andthen washed with water and dried, thereby support (B7) was obtained.Image-Forming Layer Coating Solution (8) Water 30 g Fine particles (interms of solid content) 2.0 g Megafac F-171 (fluorine-containingsurfactant, 0.1 g manufactured by Dai-Nippon Ink & Chemicals Inc.)Polyvinyl alcohol (PVA PVA205, manufactured 0.2 g by Kuraray Co., Ltd.)Hexamethoxymethylmelamine 0.02 g Image-Forming Layer Coating Solution(9) Water 30 g Fine particles (in terms of solid content) 2.0 g MegafacF-171 0.1 g Polyethylene glycol (weight average molecular 0.2 g weight:2,000) Hexamethoxymethylmelamine 0.02 g Image-Forming Layer CoatingSolution (10) Water 30 g Fine particles (in terms of solid content) 2.0g Megafac F-171 0.1 g Polyvinyl pyrrolidone (weight average molecular0.2 g weight: 20,000) Hexamethoxymethylmelamine 0.02 g

[0187] Thus-obtained lithographic printing plate precursor capable ofon-press development was subjected to exposure in the same manner as inExample I and printing was performed. As a result, on-press developmentand printing were effected with every printing plate precursor with noproblem. The printable number of sheets of every printing plate and thelevel of staining resistance are shown in Table 3 below. TABLE 3Examples III-1 to III-16 and Comparative Example III-1 Kind of Image-Forming Layer Printable Coating Kind of Fine Number of Staining ExampleNo. Support Solution Particles Sheets Resistance Example III-1 B1 (8)(31) 20,000 Good Example III-2 B2 (8) (31) 22,000 Good Example III-3 B3(8) (31) 21,000 Good Example III-4 B4 (8) (31) 24,000 Good Example III-5B5 (8) (31) 23,000 Good Example III-6 B6 (8) (31) 22,000 Good ExampleIII-7 B7 (8) (31) 21,000 Good Example III-8 B5 (8) (32) 23,000 GoodExample III-9 B5 (8) (33) 23,000 Good Example III-10 B5 (8) (34) 22,000Good Example III-11 B5 (8) (35) 24,000 Good Example III-12 B5 (8) (36)23,000 Good Example III-13 B5 (9) (31) 35,000 Good Example III-14 B5 (10) (31) 30,000 Good Example III-15 B5 (9) (32) 22,000 Good ExampleIII-16 B5  (10) (32) 23,000 Good Comparative B5 (8) (iii) 1,000 GoodExample III-1

[0188] It can be seen from the above results that the lithographicprinting plate precursors according to the present invention have goodon-press developing property, excellent press life and stainingresistance.

EFFECT OF THE INVENTION

[0189] The present invention can provide a lithographic printing plateprecursor capable of plate-making by scanning exposure on the basis ofdigital signals and having good on-press developing property andexcellent press life.

[0190] While the invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope thereof.

What is claimed is:
 1. A lithographic printing plate precursor whichcomprises an image-forming layer which contains a hydrophilic resin, anacid precursor and at least one component selected from fine particlescontaining a compound having a vinyloxy group and microcapsulescontaining a compound having a vinyloxy group, on a hydrophilic support.2. A lithographic printing plate precursor which comprises animage-forming layer which contains a hydrophilic resin, an acidprecursor and at least one component selected from fine particlescontaining a compound having an epoxy group and microcapsules containinga compound having an epoxy group, on a hydrophilic support.
 3. Alithographic printing plate precursor which comprises a hydrophilicsupport having provided thereon an image-forming layer containing fineparticles containing a thermosetting compound, and a hydrophilic resin.4. The lithographic printing plate precursor as claimed in claim 1,wherein the fine particles containing a compound having a vinyloxy groupor the microcapsules containing a compound having a vinyloxy groupcontain at least one component of an acid precursor and an infraredray-absorbing dye.
 5. The lithographic printing plate precursor asclaimed in claim 1, wherein the fine particles containing a compoundhaving a vinyloxy group or the microcapsules containing a compoundhaving a vinyloxy group contain a compound having a functional groupwhich reacts with a vinyloxy group.
 6. The lithographic printing plateprecursor as claimed in claim 1, wherein the hydrophilic resin containsa functional group which reacts with a vinyloxy group.
 7. Thelithographic printing plate precursor as claimed in claim 2, wherein thefine particles containing a compound having an epoxy group or themicrocapsules containing a compound having an epoxy group contain atleast one component of an acid precursor and an infrared ray-absorbingdye.
 8. The lithographic printing plate precursor as claimed in claim 2,wherein the fine particles containing a compound having an epoxy groupor the microcapsules containing a compound having an epoxy group containa compound having a functional group which reacts with an epoxy group.9. The lithographic printing plate precursor as claimed in claim 2,wherein the hydrophilic resin contains a functional group which reactswith an epoxy group.
 10. The lithographic printing plate precursor asclaimed in claim 3, wherein the fine particles containing athermosetting compound contain an infrared ray-absorbing dye.
 11. Thelithographic printing plate precursor as claimed in claim 3, wherein thethermosetting compound is at least a resin selected from a resin havinga phenolic skeleton, a melamine resin and a urea resin.
 12. Thelithographic printing plate precursor as claimed in claim 1, wherein thehydrophilic support is an aluminum support which has been subjected toanodization treatment and hydrophilization treatment.
 13. Thelithographic printing plate precursor as claimed in claim 2, wherein thehydrophilic support is an aluminum support which has been subjected toanodization treatment and hydrophilization treatment.
 14. Thelithographic printing plate precursor as claimed in claim 3, wherein thehydrophilic support is an aluminum support which has been subjected toanodization treatment and hydrophilization treatment
 15. Thelithographic printing plate precursor as claimed in claim 1, wherein theprinting plate precursor is development processed on a printing machine.16. The lithographic printing plate precursor as claimed in claim 2,wherein the printing plate precursor is development processed on aprinting machine.
 17. The lithographic printing plate precursor asclaimed in claim 3, wherein the printing plate precursor is developmentprocessed on a printing machine.